EP0723661A1 - Measurement method for continuous monitoring of the condition of materials - Google Patents
Measurement method for continuous monitoring of the condition of materialsInfo
- Publication number
- EP0723661A1 EP0723661A1 EP94929566A EP94929566A EP0723661A1 EP 0723661 A1 EP0723661 A1 EP 0723661A1 EP 94929566 A EP94929566 A EP 94929566A EP 94929566 A EP94929566 A EP 94929566A EP 0723661 A1 EP0723661 A1 EP 0723661A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- measurement method
- signal
- passed
- counter
- emission
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
Definitions
- the present invention relates to a measurement method indicating the structures and condition of materials, which method is based on acoustic emission and makes it possible to detect the changes taking place in the structures of materials starting from a diffusion with a size of one lattice pitch up to a macroscopic crack and to measure them in real time.
- the field of use of the method includes all materials emitting sound.
- the measurement method according to the invention provides a decisive improvement as far as the above-described drawbacks are concerned.
- the measurement method according to the invention is characterized by what is set forth in the characterizing portion of claim 1.
- Materials can be monitored all the time within their whole area in a real-time fashion. The behaviour of the materials can be controlled, and consequently surprising accidents leading to catastrophes can not hap ⁇ pen. The repairs can consequently be projected in advance.
- the use of materials can be optimized by changing use conditions, whereby safer and longer use life is achieved. Direct inspection costs will be consider ⁇ ably diminished, because the object is every moment under survey. De- fects in the construction are detected in advance in the beginning, and they can be amended before they grow to a critical level. The method helps also to reveal leaks from containers, thus decreasing emissions to the nature.
- Fig. 1 shows schematically a measurement method where 1 represents the object io be measured, from which elastic sounds are discharged after a defect has occurred in the material.
- Elastic waves 3 emanating from a crack 2 depicted in the figure are propagated in the material to a piezoelectric sensor 4, where the elastic vibration is transformed into an electric signal, which is passed along a coaxial cable 5 to a pre ⁇ amplifier 6, where the signal is partly filtered and amplified so that electrical disturbances will not interfere with signals travelling in the cable when they are passed to a measuring unit 7.
- the signal is taken in as an analogic signal, from which the power supply and signal are separated by means of a separator 8.
- the signal is further passed through a filtering stage 9, after which it can still be amplified with an amplifier 10.
- the threshold voltage of the input of the measuring unit can be adjusted to a desired value using a potentiometer 11 , this operation allowing to vary the threshold value of incoming signals in accordance with limits specific to the material, whereby essential data can be registered cumulatively in a counter 12.
- the counter registers only those current peaks that have exceeded the threshold value.
- the counter 12 is read by a computer 13, by means of which the data are processed and formed into a file.
- the files are transmitted by means of a transmission program and using a modem 14 and telephone line 15 to a control computer, which shows the development of emission from each sensor cumulatively as a function of time displayed 16 in real time.
- the points of study of the output of each sensor are the frequency of occurrence of emission-generated current peaks that have exceeded the threshold value, count/s, and their cumulative sum.
- the current impulses coming from the sensor are not conver ⁇ ted into a digital form, but they are treated only as an analog signal by means of a filter and an amplifier. Only filtered and restricted material specific data enter the computer processing, and the computer can transmit and construct graphic diagrams for each sensor about the development of emission on a real-time basis.
- an app- lication where various friction mechanisms such as the condition of slide bearings can be successfully measured through emission.
- a piezo sensor attached to the bearing support a current impulse is generated at the moment of mutual contact of the bearing surfaces, which results in emission.
- the current impulses so obtained indicate the contacts of slide surfaces of the bearing in the form of an increase in the counter reading. In this way the condition of the bearing and its state of lubrication can be deduced, and the bearing can be changed according to predetermined criteria.
- the use of a multivibrator 17 between the threshold value control unit 11 and the counter 12 can be mentioned as one advantageous alternative.
- the function of the multivibrator is known as such, and it is adapted to re ⁇ gulate the frequency of the incoming bursts for ensuring the correct func- tioning of the counter 12.
- the multivibrator 17 is adapted to transform the incoming peaks on the triggering principle into a square wave having a certain maximum frequency, for instance 100 kHz. If the incoming bursts have a higher frequency, the "extraneous" peaks do not cause a produce of the square wave, in this way the data entering the counter can be limited.
- the signal is analog, in the case of the multivibrator 17 in the form of square-wave pulses of certain height.
- the counter 12 counts in this way voltage pulses exceeding the predetermined threshold and originating from the threshold control 11.
- the computer reads the output of each sensor-specific counter at desired intervals in the form of a BCD number (binary coded decimal), i.e. after the counter 12 the data are processed digitally.
- BCD number binary coded decimal
- the file of the computer 13 is thereby recorded information about the count value of the counter at predetermined intervals for the survey. Further, it is possible to register the information if the change of the count value has exceeded the predetermined limit, which is the alarm limit.
- the counters, which each are connected to their respective sensors can be connected to the same computer 13, each sensor 4 being allotted its own file.
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI934530A FI100487B (en) | 1993-10-14 | 1993-10-14 | Measurement procedure for continuous control of the condition of the materials |
FI934530 | 1993-10-14 | ||
PCT/FI1994/000464 WO1995010772A1 (en) | 1993-10-14 | 1994-10-14 | Measurement method for continuous monitoring of the condition of materials |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0723661A1 true EP0723661A1 (en) | 1996-07-31 |
EP0723661B1 EP0723661B1 (en) | 2001-11-21 |
Family
ID=8538774
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94929566A Expired - Lifetime EP0723661B1 (en) | 1993-10-14 | 1994-10-14 | Measurement method for continuous monitoring of the condition of materials |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0723661B1 (en) |
AT (1) | ATE209349T1 (en) |
DE (1) | DE69429187T2 (en) |
FI (1) | FI100487B (en) |
WO (1) | WO1995010772A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002059594A1 (en) * | 2001-01-23 | 2002-08-01 | Mikhail Arsenovich Ananyan | Wide-range multifunctionnal diagnostic system |
US6829941B2 (en) | 2002-10-10 | 2004-12-14 | Andrey Gennadievich Alexenko | Tunnel effect nanodetector of mechanical vibrations and method for preparation thereof |
JP6329338B2 (en) | 2012-04-30 | 2018-05-23 | ゼネラル・エレクトリック・カンパニイ | System and method for monitoring stator vane health |
CN109752463B (en) * | 2019-03-06 | 2021-04-30 | 山东商务职业学院 | Pressure container defect detection device and detection method thereof |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3713127A (en) * | 1970-10-16 | 1973-01-23 | Trodyne Corp | Acoustic emission crack monitor |
US4024522A (en) * | 1976-03-15 | 1977-05-17 | Gard, Inc. | Acoustic emission system for welding flaw detection |
US4207771A (en) * | 1979-03-02 | 1980-06-17 | Western Electric Company, Inc. | Method and apparatus for monitoring cracking using stress wave emission techniques |
JPS58150859A (en) * | 1982-03-03 | 1983-09-07 | Hitachi Ltd | Method and apparatus for diagnosing crack of rotor |
GB2132352A (en) * | 1982-12-17 | 1984-07-04 | British Gas Corp | Corrosion detection |
US4531411A (en) * | 1983-10-25 | 1985-07-30 | The United States Of America As Represented By The United States Department Of Energy | Acoustic emission linear pulse holography |
US4738137A (en) * | 1986-06-12 | 1988-04-19 | The United States Of America As Represented By The Administrator, National Aeronautics And Space Administration | Acoustic emission frequency discrimination |
US5293555A (en) * | 1991-05-24 | 1994-03-08 | Hughes Aircraft Company | System and method for locating material fatigue using multiple sensors |
-
1993
- 1993-10-14 FI FI934530A patent/FI100487B/en not_active IP Right Cessation
-
1994
- 1994-10-14 DE DE69429187T patent/DE69429187T2/en not_active Expired - Lifetime
- 1994-10-14 WO PCT/FI1994/000464 patent/WO1995010772A1/en active IP Right Grant
- 1994-10-14 AT AT94929566T patent/ATE209349T1/en not_active IP Right Cessation
- 1994-10-14 EP EP94929566A patent/EP0723661B1/en not_active Expired - Lifetime
Non-Patent Citations (1)
Title |
---|
See references of WO9510772A1 * |
Also Published As
Publication number | Publication date |
---|---|
DE69429187D1 (en) | 2002-01-03 |
WO1995010772A1 (en) | 1995-04-20 |
FI934530A (en) | 1995-04-15 |
ATE209349T1 (en) | 2001-12-15 |
DE69429187T2 (en) | 2002-07-11 |
FI100487B (en) | 1997-12-15 |
EP0723661B1 (en) | 2001-11-21 |
FI934530A0 (en) | 1993-10-14 |
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